Are you using the LabVIEW instrument driver? If not, go to http://ni.com/idnet/, and search for "33120a". I downloaded the LabVIEW Plug and Play driver--i.e., the native LV source code driver. (There are also CVI and IVI drivers available.)
Anyway, if you download this driver, the VI you want is called "ag33xxx - Config Outp Term.vi".
I hope this helps.
Brian